Super-cool synapses

A chilling new technique shows the intricate and coordinated activity of previously mysterious pieces of the synapse, the all-important junction between neurons that allows cells to talk to each other.

To capture this pretty picture, the researchers used a complex technique called electron cryotomography. They first froze rat brain cells in action at temperatures as low as -165 degrees Celsius, then looked at the cells at different angles using an electron microscope and, finally, reconstructed them in three dimensions on a computer.

There are other methods to look at synapses, but they require cells to be fixed in chemicals for a long time, which can distort the final product. Light microscopy, a much older and more popular technique, illuminates living cells, but only down to 400 nanometers.

The technique reveals the workings of some of the tiny protein filaments scattered across a synapse, whose role had been largely unknown before. One type of filament, dubbed 'tethers', anchors synaptic vesicles — the bubble-like structures that shuttle chemical messengers inside the cell — to the cell membrane. That way, when the cell receives the appropriate electric signal, the vesicles are in the right position to release the chemicals into the synapse.